Field of the Invention
The present invention relates to a powertrain for an automotive vehicle with a variable-speed transmission device comprising a triple epicyclic gear train which in particular a powertrain for a hybrid type vehicle.
Description of the Prior Art
This type of vehicle comprises a powertrain that uses, alone or in combination, as a traction/propulsion drive, a thermal engine, generally of internal-combustion type, with a speed variation device and a driving and receiving machine, like a rotary electrical machine connected to an electrical source, such as one or more electrical accumulators or batteries. This combination allows optimizing the performance of this vehicle, by reducing the discharge of emissions to the atmosphere as well as the fuel consumption. Thus, when the vehicle is to be driven with a high torque over a wide speed range while limiting exhaust gas and noise generation, as in an urban site, the electrical machine is preferably used for driving this vehicle. The thermal engine is used for driving this vehicle for uses where a high driving power and a wide operating range are required.
As is already known from French patent application No. 2,955,165 filed by the applicant, the automotive vehicle powertrain comprises a thermal engine with a shaft connected to a variable-speed transmission device including an engine epicyclic gear train with a sun gear and a crown each connected to the thermal engine shaft by a controlled coupling and to a fixed part of the powertrain by a one-way automatic coupling, and a planet gear carrier transmitting the speed variation to the drive axle of the vehicle through a transmission track comprising the elements contained between the planet carrier shaft and the axle, which provide kinematic connection between the shaft and the axle.
In order to increase the speed variation capacity when the vehicle is driven on the electrical machine, the applicant has combined the variable-speed transmission device of the aforementioned document with another epicyclic gear train connecting the engine epicyclic gear train to the track for motion transmission to the drive axle of the vehicle, as described in French patent application No. 2,962,697 filed by the applicant. In this configuration, the transmission track also comprises all the elements contained between the planet carrier shaft of the other epicyclic gear train and the axle.
Although it performs adequately, the applicant has further improved this speed variation device by making it possible to increase the number of gear ratios by use of a variable-speed transmission device of simple and inexpensive design.